Malingering

To enact or exaggerate disability Conscious simulation Expression highly variable No definitive means of detection

Many reasons for poor test performance

Once detected evidence of cognitive abnormality need to determine basis of those deficits

- Neurological syndrome under investigation- Enactment/exaggeration- Other neuropsychological risk factors

No definitive means of detection

However, there are scientific means to expose attempts to exaggerate cognitive impairments and to provide objective evidence of deliberate attempts to achieve poorly.

Tests most often employed

15-Item Visual Memory Test Digit Repetition Test of Memory Malingering Word Memory Test Recognition Memory Test ACS Effort Measures: LM, VPA, VR, RDS, Des

MMPI-II

15-Item Visual Memory Test

A B C

1 2 3

a b c

O □ I II III

15-Item Visual Memory Test

Lezak: Anyone who is not significantly deteriorated can recall at least three of the five character sets

Frequently used cut-off = 9/15

A B C D

1 2 3 4

I II III IIII

A B S

1 2 3

A P O

Τ

A P D

I C O

I O 1

15-Item Visual Memory Test

Good specificity Poor sensitivity

Digit Repetition

Contrasts between (WMS-IV) Memory and

Visual Working Memory Contrasts between (WAIS) VC and

Working Memory

Reliable Digit Span

Sum of the longest string of digits recalled on both trials of each digit length for both forward and backward condition.

Score of 7 or less suggestive of malingering/exaggeration

Supraspan Learning

Sensitivity, specificity data not available

Simple task with face validity

Stimulus:9, 1, 8, 4, 2, 7

Response1. 5, 8, 4, 72. 9, 1, 8, 4, 73. 9, 1, 8, 74. 9, 8, 4, 75. 9, 1, 8, 4, 2, 7 (correct)6. 9, 1, 4, 2, 77. 9, 1, 2, 7 no 4, 78. 9, 1, 4, 8, 2, 79. 9, 1, 4, 2, 8, 710. 9, 1, 8, 4, 2, 7 (correct)11. 9, 1, 4, 2, 8, 7

Case example 2

Digit Span

3 items forward unreliably

3 items backwards unreliably

Stimulus7, 5, 8, 3, 6

Response1. 7, 5, 8, 62. 5, 8, 3, 73. 7, 5, 6, 34. 7, 8, 5, 65. 7, 5, 3, 8, 66. 8, 5, 7, 67. 7, 8, 3, 5, 68. 8, 7, 5, 69. 7, 8, 5, 6, 310. 8, 7, 5, 3, 6

Not only were her answers highly improbable, but her first attempt at the task confirmed that she could hold at least three numbers in mind (which her extremely poor performance on the Digits Forward section of the WAIS-III Digit Span subtest would suggest that she could not). Considered in conjunction, her results on the tests detailed above provided clear evidence of a deliberate attempt to exaggerate cognitive impairment.

NB: frequently asked whether reference to fatigue, headache, pain, depression etc etc (or some combination of these factors) could explain the poor performances.

Test of Memory Malingering

50 items, two trials Recognition memory – forced choice

Score of below 45/50 suggestive of malingering

Research has demonstrated that performance on the test is unaffected by affective status (Rees, Tombaugh and Boulay, 2001; Ashendorf et al 2004)

Some work done with children suggesting that from a young age (6 years) it is appropriate.

Good specificity ? Sensitivity

Word Memory Test

50 words presented to the patient in pairs

DOG CAT

COMPUTER TERMINAL

MILK COFFEE

Recognition Memory Testing – forced choice

Eg DOG RABBIT

High Sensitivity

???Specificity

Merten, Bossink and Schmand, JCEN, 2007

Highlight the fact that the WMT may not be appropriate for severely impaired patients.

Inconsistencies Bizarre or unusual performance Performance levels below the usual range

for persons who have complained of symptoms or disorder on an organic basis

Failure on all tasks (irregardless of function or level of difficulty)

Malingering does not exclude the possibility of brain damage

Feigning of an illness may be symptomatic of that illness

Malingering does preclude accurate assessment of the nature and degree of ‘real’ disability

Question of enactment or exaggeration most often arises in the context of a medico-legal assessment – clear incentive to perform poorly

However, any clinician must always be aware that exaggeration may occur.

In this context that one must be acutely aware of the expected outcome following any neurological insult.

Eg Severity of TBI and expectations of nature and magnitude of any residual deficits

Course of deficits over time.

CASE: M.V.

33 y.o female Education; Year 11

19/11/04: assaulted during the course of her work (manager of a TAB agency for 5 years)

Taken to a local medical centre, examined and sent home

12/12/04: Consulted her local doctor complaining of headaches, paraesthesia of the right thigh, memory loss and an inability to count and spell

Angiography: Marked diffuse narrowing of the L ICA ( a result of carotid dissection)

Ax: 9/10/05

WAIS-R - Why

WAIS-IV SS SS

Info 10 Matrix Reas. 5

Similarities 6 Visual Puzz 4

Vocab 12 Block D. 4

Arith 1 Coding 2

Digit Span 2 Symbol Search

2

Arithmetic- Unable to answer even items 1 and 2

Digit Span - 3 Forwards unreliably- 3 backwards reliably

Coding- Reversed most (but not all) items

WMS-IV

Auditory Memory = 74Visual Memory = 60Visual Working Memory = 50Immediate Memory = 67Delayed Memory = 58

15-Item Visual Memory Test

Trial 1 = 4/15

Trial 2 = 4/15

RMT

Faces = 16/50*

*Below chance – meaning??

Case: JH

43 yo male

TBI: 21/6/04 struck as a pedestrian while crossing road

Claimed to remember stepping onto main road. Having to cross in front of three lanes of traffic. Passing in front of two lanes and then “bang” as was hit

In hospital for two to three days

???? Length of PTA

*Single best measure of TBI severity

Often difficult to determine in malingering population

- ? Validity of any report- Often claim that memory still has not returned

Chief subjective complaint was of a dense retrograde amnesia

- Could remember his parents- No recollection of primary, secondary or tertiary studies.

Reported that he “probably” completed a degree in law and “maybe” a masters degree in that subject

- Reports indicated that he came to Australia in 1996. No recollection of having done so

- No recollection of establishing or operating the bakery that he did while in this country.

WAIS-IV

Matrix Reasoning 4

Visual Puzzles 4

Block Design 5

Digit Symbol 2

WMS-IV

Visual Memory 71

Visual Working Mem. 50

Supraspan Learning

6, 1, 7, 4, 8, 2

20 trials – still unable to repeat correctly over two consecutive trials

15-Item Visual Memory Test

No rows correctly reproduced (see below)

Recognition Memory Test

Faces 26/50